As the surfactant usable for detergents, those in a liquid form are well used. For instance, a nonionic surfactant having excellent detergency performance against sebum dirt stains is in a liquid state or pasty state at an ordinary temperature. In addition, much of anionic surfactants are solid, and they are often used in the form of aqueous solutions from the viewpoint of easiness in handling.
As a process of using the liquid surfactant described above in a powder detergent, a composition containing the surfactant may be supported in the particles. As the particles for uses described above, those having a large absorption amount (supporting ability) of the surfactant are preferable, from the viewpoint of suppressing the bleed-out of the surfactant. In a case where the surfactant cannot be sufficiently supported in the particles, an oil-absorbing carrier having a high supporting ability or the like is usually used for the purpose of maintaining the properties as the powder detergent. However, the oil-absorbing carrier does not contribute much to the detergency performance. Therefore, reduction in the amount used is demanded, from the viewpoint of the quality of the powder detergent.
The techniques purposed for improvement in the supporting ability include those techniques disclosed in Japanese Patent Laid-Open No's. Sho 57-159898 and Sho 62-112697. In these techniques, however, since a substance unnecessary for the detergency performance is formulated and a compositional limitation is necessitated, for achieving the above-mentioned objects, there is a concern for lowered detergency in exchange for the improvement in the supporting ability.
One of the particles formulated with the detergent composition is spray-dried particles obtained by spray-drying a slurry containing water-soluble components such as a water-soluble salt and a water-soluble polymer. When the spray-dried particles are used as particles supporting a surfactant, since the particles have a structure such that the surface is coated by a film containing the water-soluble component from its production process, it has been difficult to increase its supporting ability.